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In this paper, we introduce a meander-feed antenna system featuring circular polarization (CP) diversity and high isolation. The antenna design comprises a monopole antenna and an isosceles triangular partial ground on a single layer. This innovative structure departs from traditional antennas in three significant ways: it achieves structural asymmetry by modifying the antenna's shape and position, which enhances CP characteristics; and it transitions the feeding structure from a linear to a meander type. Experimental results show that the proposed antenna covers frequency ranges of 6.9–8.5 GHz and 9.2–10.1 GHz, with measured isolation below − 12 dB within the operating bandwidth. As a result, the single monopole antenna attains a CP bandwidth of 20.78% and 9.33%. The single-element CP antenna is then incorporated into a 4-port MIMO antenna, which is fabricated and measured, demonstrating excellent agreement between simulated and measured results. The proposed antenna system achieves an overall gain of 5 to 8 dBi across the operating spectrum, making it an ideal choice for X-band applications. [ABSTRACT FROM AUTHOR]

Low‐profile miniaturized wideband circularly polarized (CP) monopole and multiple‐input‐multiple‐output (MIMO) antennas using characteristic mode analysis (CMA) are presented. The antennas are constructed with a microstrip feeding line, a slot, and a branch, which positions the transmission line perpendicularly to the branch to achieve CP. The CP characteristic is realized through a characteristic angle (CA) difference of approximately 90° at three mode significance (MS) intersections across four modes. CMA provides both theoretical analysis and design guidance for these antennas. The antennas were fabricated and tested, with dimensions of 0.48λ₀ × 0.48λ₀ × 0.03λ₀ and 0.47λ₀ × 0.47λ₀ × 0.03λ₀, where λ₀ represents the free‐space wavelength. Measurements indicate that the monopole antenna achieves a −10 dB impedance bandwidth (IBW) from 3.2 to 8.4 GHz (89.7% relative bandwidth), a 3 dB axial ratio bandwidth (ARBW) from 3.6 to 5.1 GHz (34.5%), and a peak gain of 6.6 dBic. The MIMO antenna has a −10 dB IBW from 3.1 to 8.2 GHz (90.3%), a 3 dB ARBW from 3.2 to 6 GHz (60.9%), and a peak gain of 5.1 dBic. Both antennas feature a low profile, ultra‐wideband IBW, broadband ARBW, and miniaturized design, making them suitable for wideband wireless communication applications. Key Points: Low‐profile miniaturized wideband circularly polarized (CP) monopole and multiple‐input‐multiple‐output (MIMO) antennas using CMAThe microstrip feeding line and slot and the branch, which makes the transmission line perpendicular to the branch to obtain the CPThe CP characteristic can be achieved by a CA difference of approximately 90° at three intersections of MS for four modes [ABSTRACT FROM AUTHOR]

This article presents a systematic design and optimization process for a compact 0.27λ0 × 0.31λ0 multiband monopole antenna for Internet of Vehicles (IoV) applications, including navigation, Vehicle to Infrastructure (V2I), Wi-Max, and 5G. The antenna's modified ground plane enables installation within a shark-fin module on a car roof, aligning with its low-profile dimensions and high performance. Structural modifications to the initial antenna element, including the T-shaped structure and integrated stub between quad rings, enable circular polarization in the GPS L1 band. With simulated total radiation efficiency exceeding 60% at four bands, numerical simulations and physical fabrication on an FR-4 substrate are followed by antenna radiation measurement in an anechoic chamber. The measured gain at 1.575 GHz, 2.6 GHz, 4.8 GHz, and 8 GHz is 1 dBi, 2.2 dBi, 3.2 dBi, and 3.8 dBi, respectively. Additionally, ray tracing techniques evaluate the antenna's performance when mounted on a car, considering interactions with other vehicular antennas and infrastructure in urban propagation scenarios. Urban propagation analysis illustrates efficient operation, characterized by minimal delay time, favorable line of sight, and controlled path loss at frequencies 2.6 GHz and 4.8 GHz. These findings demonstrate the antenna's potential for adoption in the automotive industry. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of a low-profile 8 × 8 multi-input-multi-output (MIMO) antenna with zero ground clearance, designed using an intelligent antenna recommender system. A dissimilar antenna pair is employed to achieve multi-band resonance and enhance isolation for sub-6G mobile communication. The primary antenna is a loop antenna resonating at n77, n79, and n46 bands, designed with the aid of a model developed using a support vector machine (SVM). The auxiliary antenna is a modified monopole resonating at n78 and n79 bands to minimize the antenna footprint on mobile devices. An eight-antenna MIMO array is fabricated, and measured results demonstrate that the proposed antenna has a reflection coefficient of less than − 10 dB at 3.5, 3.7, 4.5, and 5.2 GHz, with diversity gain and isolation greater than 9 dBi and 15 dB, respectively. SAR analysis conducted on a human head model shows a maximum SAR value of less than 1.6 W/kg at all sub-6G bands, compliant with FCC standards. The proposed MIMO antenna offers a viable solution, even when integrated with a battery and display, without occupying internal space within a mobile phone. [ABSTRACT FROM AUTHOR]

The diffuse field sound absorption coefficient (SAC) of a sound absorber can be obtained from an average over the incidence angles of the oblique incidence plane wave SAC. The plane wave SAC can be derived from the plane wave complex-valued reflection coefficient defined as the ratio of the reflected sound pressure at a given point on the material surface to the incident sound pressure at the same point. In practice, the material is excited by a monopole, and the reflection coefficient becomes a local quantity which is a function of the source height and the radial distance from the source. This local reflection coefficient obtained at various points on the material surface is commonly used to approximate the oblique incidence plane wave reflection coefficient. The error in estimating the diffuse field SAC introduced by this approximation has not been explored in the literature. This paper investigates this error as a function of the material extent, thickness, and source height using an analytical approach to calculate the local reflection coefficient. The calculation is based on Allard's model which describes the sound propagation above an infinite lateral extent porous material backed by a rigid wall and excited by a monopole. Using finite element simulations as a reference, the analytical model is shown to provide a good approximation of the diffuse field sound absorption performance of sufficiently large material areas. The diffuse field SAC calculated from plane wave reflection coefficients and local reflection coefficient are compared. The limitations inherent in deriving diffuse field SACs from local reflection measurements obtained with a monopole are highlighted. [ABSTRACT FROM AUTHOR]

Over the past years, remote sensing, radar, and imaging applications have all made use of ultra-wideband (UWB) technology. This study undertakes an extensive analysis of tree-shaped monopole antennas tailored for UWB systems. The intended antenna has an incomplete ground plane and a circular radiating patch. To increase bandwidth, two ears have been added to the circular structure. Possessing a dielectric constant of 4.3. The antenna substrate consists of FR-4 material with a dielectric constant of 4.3. To achieve optimal impedance matching for UWB systems, the antenna is fed via a coplanar waveguide (CPW). Design antenna is a simple structure, small size, easy design, and simple integration with the substrate with dimensions of 54 mm ×36 mm ×1.6 mm. All simulation results presented in this article were generated using computer simulation technology (CST) software. He monopole antenna exhibits an impressive impedance bandwidth of 9.6 GHz (146.68%), spanning from 1.99 GHz to 11.56 GHz. Furthermore, the simulated UWB circular monopole antenna exhibits omnidirectional radiation characteristics, boasting a peak gain of 8 dB, and a directivity of 8.2 dBi at the frequency of 5 GHz, and a remarkable radiation efficiency of 97%. With these attributes, the suggested monopole UWB antenna shows significant potential for ground penetrating radar (GPR) applications. [ABSTRACT FROM AUTHOR]

Monopile foundations are commonly constructed for offshore wind turbines and installed at depths shallower than 30 m. However, preventing scouring and erosion around the pile foundation due to waves is critical, as this can cause instability of the foundations and supported structures. In this study, model and numerical tests were conducted to investigate wave-induced scour and erosion around a monopile foundation and clarify the fundamental mechanisms involved. Numerical tests were conducted and validated against physical model tests for a bare sea bed, and good reproducibility was obtained. When a monopile foundation was installed in both the numerical and physical tests, the flow velocity on the seabed in the offshore and inshore directions increased on the side of the foundation perpendicular to the direction of the wave motion. In the model test, scouring occurred at the same location, indicating that scouring may have been caused by the flow velocity; however, this scouring occurred locally, suggesting the need for a detailed analysis of the associated factors. [ABSTRACT FROM AUTHOR]

A rectangular patch microstrip antenna is a tool for wireless communication, suitable due to its advantages such as being low profile, low cost, easy to connect with electronic circuits, and light weight. We introduce a way to increase band width by introducing the technique of reconfigurable patching and tuning of the width of the ground plane. Three steps are done to get the final design, which results in significant effects on return loss and demonstrates bandwidth broadening compared with a traditional rectangular patch antenna. An extensive analysis was conducted to determine the optimal dimensions and parameters of the proposed antenna, including the ground plane width, slot width and length, the gap between the patch edge and ground plane, and the offset of the strip line feed. The optimal dimensions were determined to maximize the performance of the proposed antenna. The optimal dimensions for the width and length of the patch slots are determined to be 2.8 and 7.5 mm, respectively, with a ground plane height of 14.5 mm. The best offset value for strip line feed is -1.5 mm for the y-axis. Finally, the overall bandwidth achieved from the proposed antenna is 10.47 GHz, covering the ultra-wideband range. There are many applications, such as improved Bluetooth, Wi-Fi, Wi-Max, and satellite communication. [ABSTRACT FROM AUTHOR]

A four elements MIMO (Multiple Input Multiple Output) antenna with improved isolation and compact size of 32 × 32 × 0.8 mm3 is proposed for C, X, Ku, K & Ka bands applications. This antenna also covering a band proposed for 6G communication (7–20 GHz). Initially, a ring-shaped elemental monopole patch antenna integrated with four perpendicular spaced spoke and staircase shaped DGS below fed line has been proposed. The elemental antenna shows a better reflection coefficient, good gain and directional radiation pattern at different frequency like X band (8–12 GHz), Ku band (12–18 GHz), K band (18–26.5 GHz) and Ka band (26.5–40 GHz) operating from 5.8 to 40 GHz with bandwidth of 34.2 GHz. To utilize the proposed antenna in multipath propagation environment MIMO configuration has been opted. Initially, a two-element based MIMO is investigated, finally the four element MIMO with a meshed metamaterial in ground to mitigate the problem of interferences among different elements of antenna has been done. Due to MIMO an improvement in bandwidth from 3.2–45 GHz is also observed covering C band (4–8 GHz). The proposed MIMO have an improved ECC, DG, TARC, Peak Gain and Group delay. Impedance circuit with passive elements is also observed using ADS software. [ABSTRACT FROM AUTHOR]

This paper investigates the relation between the Berry phase of a spinor accumulated along a path corresponding to an adiabatically varying magnetic field and the conformal deformation along the path in the parameter space. The first part demonstrates that the accumulated phase can be controlled by continuous deformation characterized by a single conformal parameter. The source of the corresponding field strength responsible for the deformed phase path is shown to be a conformally deformed monopole located at the origin in the parameter space with the fundamental strength g=±1/2. In the second part, we model a rotating magnetic field coupled to a charged spinor with a time-varying amplitude subjected to the conformal deformation, realizing a single-variable deformation of the evolution process of the phase path.

In this work, a dual-band dual circularly polarized coplanar waveguide (CPW)-fed monopole antenna is presented. The antenna consists of the modified ground plane, and two rectangular-shaped radiators, which are located on the two sides of the monopole. The radiating patches are loaded with metamaterial dependent electromagnetic band-gap structures for obtaining wider impedance bandwidth and broad axial ratio characteristics. The proposed antenna features impedance bandwidth of 97.4% (1–2.9 GHz) in the first band and 61.36% (3.05–5.75 GHz) in the second band, covering applications of ISM-band (2.4–2.48 GHz), Wi-MAX (2.5–2.69 GHz, 3.4–3.69 GHz), and WLAN (2.4–2.48 GHz, 5.15–5.35 GHz). The antenna also features dual circular polarization with 3-dB axial ratio bandwidth of 33.8% (1.35–1.9 GHz) and 35.7% (3.1–4.45 GHz), in the first and second bands, respectively. The first band shows right-hand circular polarization, whereas the second band exhibits left-hand circular polarization. [ABSTRACT FROM AUTHOR]

This paper investigates discrete symmetries for dyon and the invariance of Maxwell's field equations in the macroscopic media (material medium). Using advanced mathematical approaches, the paper derived electromagnetic duality and a unique form of Poynting theorem for dyon in macroscopic media. Here, we demonstrate that the combination of parity (P) , charge conjugation (C) , and time reversal (T) symmetry: CPT , is an exact symmetry for dyon in macroscopic media. Furthermore, a comprehensive analysis of the electromagnetic wave equation for dyons in conducting media is also derived. These findings contribute significantly to the understanding of dyon behavior in electromagnetic fields. [ABSTRACT FROM AUTHOR]

This communication presents a wideband and a low-profile flexible wearable antenna intended to operate at a 2.45 GHz WBAN band. The suggested antenna comprises a CPW-fed monopole antenna backed by an artificial magnetic conductor (AMC) to act as a reflector. The latest AMC-integrated design uses R03003 as a dielectric substrate. The suggested design features an impedance bandwidth of 71.03% (1.87–3.93 GHz) with a gain value of 3.62 dBi and has a compact footprint of 40 × 40 mm2. The incorporation of wideband AMC with a monopole antenna leads to bandwidth enhancement and covers the 3.5 GHz WiMAX band. Simulation and experimental studies provide evidence that in the case of structural deformities and human body loading, the suggested AMC-integrated antenna is stable and shows superior efficiency relative to the traditional monopole antenna. Furthermore, numerical analysis demonstrates that the amount of radiation AMC-integrated antenna decreases tremendously in terms of specific absorption rate for various bodily attachment scenarios. Three body templates with various compositions and forms were used to study the effects of the antenna on bodily attachment. Extensive experiments on human body phantoms and bodily attachment are also conducted and the results are presented. The suggested AMC-integrated design thus confirms a promising contender for portable wearable wireless applications. [ABSTRACT FROM AUTHOR]

The Octa-band frequency reconfigurable antenna proposed in this paper can operate in the UWB, GSM, WiMax, 5G MID BAND, WLAN (C-BAND), WLAN (S-BAND), 5G (C-BAND), and STM link-1 bands. To achieve the desired operating frequency, the ground plane of the UWB monopole antenna is modified by embedding two inverted L-shape slots. A novel frequency selective surface (FSS) reflector consisting of a 5 × 5 array of elements is located at a distance of 0.78λ at 6.2 GHz below the proposed reconfigurable antenna to improve its gain. The addition of FSS resulted in a gain improvement of 3–7 dBi. The proposed antenna has a wide switching capability, allowing it to be integrated into portable electronic devices and making it suitable for 5G and other wireless applications. [ABSTRACT FROM AUTHOR]

This paper presents a dual-band printed monopole antenna backed with an electromagnetic band-gap (EBG) array for LTE, WLAN, Wi-MAX, and ISM band applications. The antenna is comprised of a T-shaped monopole, 50 Ω microstrip feed line, and a rectangular-shaped partial ground plane. The printed monopole antenna is supported by a 6 × 6 array of EBG unit cells, with each unit cell composed of square and circular rings, resulting in a wide impedance bandwidth and improved gain. The EBG-backed printed monopole antenna with partial ground plane offers an impedance bandwidth of 57.8% (1.6–2.9 GHz) and a maximum radiation efficiency of 95.4% with a peak gain of 6.9 dB in the first band, and an impedance bandwidth of 53.24% (3.39–5.85 GHz) and a maximum radiation efficiency of 95.2% with a peak gain of 8.7 dB in the second band. The proposed monopole antenna design is miniaturised, has less design complexity, and does not require vias for EBG realisation. [ABSTRACT FROM AUTHOR]

Designing antennas for vehicular communication systems presents several unique challenges due to the dynamic nature of vehicular environments, mobility, and the need for reliable connectivity. A wider bandwidth is a critical requirement of vehicular antennas. In this paper, a super-wideband FR4 epoxy-based low-cost meander line patch antenna is designed for fifth-generation (5G) vehicular mobile frequency applications. The proposed antenna is excited through a microstrip feedline on top of the substrate with a continuous ground plane. The meander line is implemented through a theoretical formula to cover upper-5G frequency range 1 (FR1) and frequency range 2 (FR2). The proposed antenna has 7.5 dBi peak gain when operated at 28 GHz. The simulated bandwidth ratio (BWR) is 9.09:1 for a −10 dB reflection coefficient covering a 53.4 GHz (6.6 GHz to 60 GHz) frequency range. The proposed antenna has a linear meander line planar structure, occupies a small area of 34 mm × 20 mm × 1.6 mm, and satisfies the bandwidth requirements of 5G millimeter-wave and sub-bands of the sixth generation for vehicular applications. [ABSTRACT FROM AUTHOR]

A sriyantra/srichakra-shaped wideband fractal-based monopole antenna is designed and substrate material analysis is performed to determine its ability to meet the needs of S-, C-, X-, and Ku-band communication applications. The proposed model design is inspired by sriyantra, which is believed to be a source of energy to the universe according to Indian mythology. This work is focused on the integration of fractal geometry with sriyantra/srichakra for providing a linkage between philosophical belief and a modern communication system with experimental validation. The designed antenna performance characteristics are analysed on various substrates of rigid, flexible, and textile materials to identify the suitable model as per the requirements of specified applications. The proposed model provides 17.7 GHz bandwidth, a peak realized gain of 8.66 dB, and peak efficiency of 95% with RT/duroid 5880 substrate material. The design with polyimide for the proposed structure provides bandwidth of 14.8 GHz, peak gain of 6.18 dB, and peak efficiency of 90%. The same design was implemented on the fabric substrate material of bed sheet cotton, achieving bandwidth of 12.5 GHz, peak gain of 6.39 GHz, and peak efficiency of 92%. The proposed srichakra structure of the fractal monopole antenna on three substrate materials provides wide bandwidth with considerable gain and efficiency in S-, C-, X-, and Ku-band communication applications. The experimental validation provides a good correlation with the simulation results obtained from the CST (computer simulation technology) tool for applicability in communication systems. [ABSTRACT FROM AUTHOR]

This article presents a mechanically frequency-reconfigurable monopole antenna and array that offers a wide tuning range, gain enhancement, and stable beamwidth. The monopole is positioned above a large reflector plate to achieve unidirectional radiation and increased gain. By adjusting the height between the monopole and reflector plate at λ/4 according to resonant frequencies, the frequency band and gain stability can be achieved. A single-motor controlled mechanical system enables the reconfiguration of resonant frequencies and gain enhancement. Measured results demonstrate that the frequency can be adjusted from 1.17 to 3.08 GHz (basic mode) with a relative bandwidth of 89% for a single monopole over the reflector. In the tuning frequency band, the gain and radiation efficiency are 7.51±0.88 dBi and 91.9±6%, respectively. To further enhance and stabilize the gain, a method is proposed and implemented in the array application. An advanced single-motor controlled mechanical system is designed to simultaneously adjust the resonant frequencies, height between the monopole and reflector plate, and inter-distance between the elements. Measured results show that the frequency can be adjusted from 1.15 to 3.0 GHz with a relative bandwidth of 86%. The achieved gain is 11.81±0.38 dBi, and the radiation efficiency is 89.9±8.2% at the basic mode. Additionally, the 3 dB beamwidth in the reconfigured band is 61.5o±6.5o and 39.5o±5.5o for E-planes and H-planes, respectively, indicating stable radiation patterns.

This paper presents the design, development and characterization of a leaky wave plasma antenna at 2.45 GHz which has potential application in military Wi-Fi, in areas where a continuous change in frequency is required. The design of the cylindrical plasma antenna is optimized by varying the plasma tube and ground cylinder dimensions to achieve better impedance matching (S11) of the antenna. Furthermore, the axial length of the plasma generated inside the tube is directly proportional to the input excitation power, which also determines the plasma resonant frequency, making it possible to fine-tune the resonant frequency. The novelty of our work lies in two key achievements that surpass previously reported results. First, our designed antenna achieves an enhanced directivity of 4.31 dBi, coupled with a broad bandwidth of 441 MHz at 2.45 GHz. This represents a substantial improvement over prior designs. Second, and most notably, the antenna attains a high radiation efficiency of 73.8%, a benchmark not reached in earlier studies. These advancements underscore significant contributions to the field of plasma antenna technology. The designed plasma antenna is fabricated and characterized experimentally to determine its resonant frequency and scattering parameters. A 10 KHz AC power supply is used for plasma generation inside the tube. The experimental results obtained are consistent with the simulation results.

This paper presents the design and implementation of a compact, wearable, printed monopole antenna for Long-Range (LoRa) location tracking applications, covering the 915 MHz and 923 MHz LoRa bands. Fabricated on a Rogers Duroid RO3003TM substrate, the antenna integrates meandered monopoles to enable miniaturization, alongside a matching stub and a partial ground plane for enhanced impedance matching and performance efficiency. It features a bidirectional radiation pattern in the E-plane and an omnidirectional pattern in the H-plane at both frequencies, achieving a peak gain of 2 dBi and a radiation efficiency of 98% across its operational bands. With a total dimension of $50 \times 50~\text {mm}^{2}$ ( $0.153~\lambda _{0} \times 0.153~\lambda _{0}$ ), where $\lambda _{0}$ represents the free-space wavelength at 915 MHz), it represents the most compact LoRa wearable antenna known to the authors. The design, simulation, and analysis were carried out using CST Microwave Studio (MWS) software. Bending investigations showed excellent efficiency with minimal impact on bandwidth and gain, while Specific Absorption Rate (SAR) analysis indicated compliance with safety limits set by the Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) standards. SAR values at 915 MHz were measured at 0.94 W/kg for 1 gram of tissue and 0.85 W/kg for 10 grams, affirming the antenna’s suitability for wearable applications. Correspondingly, at 923 MHz, SAR values stood at 0.92 W/kg for 1 gram of tissue and 0.82 W/kg for 10 grams of tissue. Furthermore, real-world experimental validation employing the proposed antenna within a wearable LoRa tracking system revealed superior performance in LoRa localization. The average improvement in Received Signal Strength Indicator (RSSI) of 3 dBm, compared to a conventional antenna, was observed within a range of 1.5 km. This comprehensive assessment solidifies the proposed antenna’s potential as a promising and dependable solution for efficient and reliable LoRa-based location tracking across various scenarios.

L'assurance résulte d'un mécanisme financier induit par les exigences de protection des patrimoines contre les risques. Elle est donc liée au développement du commerce et aux transformations sociales. Au contraire du Banquier, l'assureur de dommages ne s'engage pas à faire fructifier et à reverser les fonds confiés par ses clients, dans le cadre d'une opération de capitalisation. Moyennant le versement d'une prime, cet assureur s'engage à régler une indemnité proportionnelle au dommage subi (principe indemnitaire) du fait d'un risque déterminé. Dans la mesure où il n'y a pas corrélation entre le montant des primes perçues par l'assureur, et l'indemnité éventuellement versée à l'assuré, toute opération d'assurance repose obligatoirement sur l'existence d'un aléa. Le législateur colonial n’a pas organisé le marché des assurances ni réglementé la profession d’assurance, tout comme il n’a pas formulé les normes devant gérer le contrat d’assurance. Il a laissé le marché et l’opérateur d’assurance évoluer suivant les règles du droit commercial général, et le contrat d’assurance soumis au droit commun de contrats, ainsi qu’aux usages des marchés étrangers d’assurance. Nous estimons que la libéralisation du secteur d'assurance est fructueuse et cela de deux points de vue : social et économique. La libéralisation implique l'existence sur le marché des plusieurs opérateurs et ces derniers permettent aux assurés d'avoir plusieurs choix sur leurs assureurs, et que l'Etat pourra contrôler rigoureusement les entreprises privées que publiques dans l'indemnisation des sinistres survenus, ou une perte, ou un évènement, d'une part et d'autre part, le secteur d'assurance est pourvoyeur d'emplois. Du point de vue économique, la libéralisation ouvre la porte aux investisseurs, qui apportent des capitaux essentiels à la construction de l'économie et sa croissance.

Designing antennas for vehicular communication systems presents several unique challenges due to the dynamic nature of vehicular environments, mobility, and the need for reliable connectivity. A wider bandwidth is a critical requirement of vehicular antennas. In this paper, a super-wideband FR4 epoxy-based low-cost meander line patch antenna is designed for fifth-generation (5G) vehicular mobile frequency applications. The proposed antenna is excited through a microstrip feedline on top of the substrate with a continuous ground plane. The meander line is implemented through a theoretical formula to cover upper-5G frequency range 1 (FR1) and frequency range 2 (FR2). The proposed antenna has 7.5 dBi peak gain when operated at 28 GHz. The simulated bandwidth ratio (BWR) is 9.09:1 for a −10 dB reflection coefficient covering a 53.4 GHz (6.6 GHz to 60 GHz) frequency range. The proposed antenna has a linear meander line planar structure, occupies a small area of 34 mm × 20 mm × 1.6 mm, and satisfies the bandwidth requirements of 5G millimeter-wave and sub-bands of the sixth generation for vehicular applications.

A novel compact antenna with characteristics of broadband and high gain is proposed in this paper. The proposed antenna comprises 1 × 2 elements that are connected together by a balance power divider. To create a new shape, the proposed antenna is a combination of dipole and patch shapes and acts as a monopole. As a result, the impedance bandwidth is enhanced. Additionally, the gain of the proposed antenna is improved by using an artificial magnetic conductor (AMC) surface. The antenna prototype, with an overall size of 0.66 λ0 x 0.79 λ0 x 0.11 λ0 (λ0 is the wavelength in free space at the lowest operating frequency of 2.63 GHz) has a −10 dB bandwidth of 78% (2.63–6 GHz), a broadside gain of 11.5 dBi, 3-dB gain bandwidth of 19%, and a total efficiency over79% in all operating frequency bands. Thanks to the presence of AMC surface and the combination ofmicrostrip and dipole shapes, the antenna resulted in an overall larger bandwidth, low sidelobe level, and higher gain and efficiency. [ABSTRACT FROM AUTHOR]

A simple and compact ultra-wideband (UWB) antenna with a novel wide band notching using Defected ground structure (DGS) based dual mode resonator is presented. This proposed dual mode resonator is not only used for band notching but also helps to increase the ground currents for better impedance matching over wide bandwidth. The antenna has a thin vertical strip structure, which yields a 10dB return loss bandwidth from 3.1to10.6 GHz, band notching from 5.15 to 5.825 GHz, cross polarization of more than 20 dB, and good omni-directional radiation pattern. The proposed antenna is compact in size and has wide band notch. It can be easily fabricated with low cost material. Hence, this proposed antenna is more suitable for wireless systems with high interference. [ABSTRACT FROM AUTHOR]

In this work, a compact, edge-fed modified rectangular patch size, monopole, and ultra-wideband antenna has been presented for their good suitability to millimeter (mm) wave and upper sub-6 GHz frequency range (FR2) for next-generation (5G and beyond) communications. The patch size enhancement approach has been utilized without affecting the original size of the substrate and rectangular patch. The technique provides better impedance matching at the designed frequency of 32.5 GHz. The minimum acceptable gain for an antenna to work well is 5 dBi. The proposed design achieves peak gain of 5.43 dBi and 10.86 dBi at two resonance frequencies of 32.5 GHz and 48.12 GHz within the specified ultra-wideband (UWB). The antenna has low loss as it is fabricated on a compact Rogers RT Duroid 5880 of thickness 1.6 mm. The measured reflection coefficients are found in good agreement with the simulated one. The resultant performance parameters like radiation pattern, reflection coefficient, peak gain, and − 10 dB bandwidth reveal that the antenna performs excellently within 26 to 40 GHz with excellent impedance matching at the resonance frequency. At higher frequencies, the time domain response of the proposed design is also presented. The RLC electrical equivalent circuit of the proposed design is presented at the end and validated using ADS software. [ABSTRACT FROM AUTHOR]

A small-size multiband antenna with 14 bands is presented in this paper for wireless applications. The studied antenna mainly consists of a folded monopole antenna and an M-shaped structure. Furthermore, the antenna has a simple design with a compact dimension of 26.8 × 10.8 mm2. The studied antenna is printed on FR4 substrate with a depth of 0.8 mm and fed by a coaxial cable. The −10 dB bandwidths measured are 210 MHz (1200–1410 MHz), 100 MHz (2200–2300 MHz), 193 MHz (3000–3193 MHz), 180 MHz (3330–3510 MHz), 390 MHz (4110–4500 MHz), 4971 MHz, 577 MHz (5300–5877 MHz), and 700 MHz (7100–7800 MHz), which can cover 3G/4G/5G/Wi-Fi/WiMAX, C, and S bands. The gain and efficiency of the presented antenna are 1.3–4.00 dBi and 46%–60.2%, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates a wideband omnidirectional antenna that possesses 124.7% of fractional bandwidth. The antenna's two crescent‐shaped radiating patches and their ultrawideband matching structures are printed on two laminates that are crossly placed vertically over the ground plane. Simulation shows that the structure on a single laminate radiates an "8"‐shaped pattern on the horizontal plane. The cross formation of the two printed laminates generates an omnidirectional radiation pattern by superimposing two "8"‐shaped patterns perpendicularly. The proposed antenna is fabricated and measured for demonstration. The measured results agree well with the simulation, indicating the omnidirectional antenna works from 1.38 to 5.95 GHz with a return loss of −10 dB. Simulation and measurement also show the gain variation on the xoy plane is 2 dB in the band of interest, which is small if the ultrawide bandwidth is considered. The above features make the proposed antenna a promising candidate for applications in the digital cellular system (DCS1800), long‐term evolution (LTE2300/2600), wireless local area network (WLAN2400), and IEEE 802.11p. [ABSTRACT FROM AUTHOR]

A rectangular monopole antenna with an extended ground, excited by Coplanar Waveguide (CPW) and backed by a 6 × 6 array of fractal artificial magnetic conductor (AMC) unit cells, resonating at 5.8 GHz in Industrial, Scientific, and Medical (ISM) band, is presented in this manuscript. To attain the objective of proposing a compact and economical antenna solution for employment in wearable biomedical domain, a novel approach of utilizing both surfaces of the same dielectric for engraving antenna element as well as AMC array is adopted. It results in the elimination of layers of expensive substrate (RO3003) and of thick separator (foam) between antenna and AMC array. During measurement in open space, the proposed antenna system exhibited an impedance bandwidth of 570 MHz with a gain of 7.9 dBi. While a total realized gain of 7.5 dBi, amounting to a gain enhancement of about 3 dB as compared to that of monopole alone, is observed when the integrated antenna system is placed just over a three-layer rectangular human body equivalent model. Specific absorption rate values, as calculated at 5.8 GHz and averaged over 1 and 10 g of human tissue, are 0.0117 and 0.00244 W/kg, respectively. Obtained results strongly advocate the use of the proposed antenna system in smart wearable healthcare devices. [ABSTRACT FROM AUTHOR]

A monopole-like stacked microstrip antenna with dual-layer patches is proposed for ultra-wideband applications. The characteristic mode analysis (CMA) is utilized and contributes to the multi-mode behavior investigation, guiding the design process. The dual-layer patches both consist of two concentric-coupled rings. The patch configuration is optimized according to the desired mode behaviors at different frequencies. Correspondingly, the three merged resonant modes, containing the modes TM01 and TM02 of the middle layer and TM01 in the top layer, effectively broaden the operation band. The measurements demonstrate that the impedance bandwidth (IBW) of the antenna reaches 4.70–10.20 GHz (73.8%) with the return loss of 10 dB and a maximum gain of 8.7 dBi. The cross-polarization level is better than −28 dB. The proposed antenna possesses a small radius of 30 mm (0.47 λ L ), and a low-profile of 5.78 mm (0.09 λ L ). λ L is the free-space wavelength at the lowest operation frequency. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a miniature two‐element Multiple Input Multiple Output (MIMO) antenna dedicated to UWB applications. The proposed MIMO design has a very low profile of 30 × 20 × 1.6 mm3. The proposed antenna is carefully designed and optimized using HFSS simulation software. As a proof of concept, the proposed design is realized and experimentally tested for MIMO applications. The proposed structure, printed on an FR4 substrate, comprises two symmetrical elliptical conductive patches on the upper side and a modified ground plane on the lower one. Each radiating element includes six elliptical rings. The modified ground plane consists of a T‐shaped strip and two semielliptical slots etched opposite the feed line. All the parameters of the design are carefully optimized to achieve an ultrawide bandwidth antenna spanning from (136.08%) 3.1 to 16.3 GHz. The results are discussed and analyzed in terms of bandwidth, gain, efficiency, radiation pattern, diversity gain, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG). All simulated results are found to be in good accordance with experiments. The design reveals attractive features for UWB applications. A good isolation (17 dB) between the two radiators is achieved despite the close proximity using the suggested ground plane geometry. [ABSTRACT FROM AUTHOR]

In this work, a dual band, reduced size, enhanced gain monopole antenna has been designed by using Frequency Selective Surface (FSS). The volume of the proposed monopole antenna is 0.14 λ 0 × 0.12 λ 0 × 0.02 λ 0 , where λ 0 is the free space wavelength at 3.5 GHz. Three L-shaped loops are used to enhance impedance matching. Size reduction and bandwidth are improved due to the L-shaped loops on the ground plane. FSS is incorporated under the monopole antenna as a band reject filter. Dual frequency bands of 3.45–3.55 GHz and 4.82–7 GHz with stable gain within the operating bands are achieved. The effect of the FSS on antenna results is studied. A maximum size reduction of 93% with 68.8% (2.18–7dBi) gain enhancement is achieved with respect to the reference antenna. The proposed antenna may be used in (5.2/5.8 GHz) WLAN, (3.5/5.5 GHz) WiMAX and fraction part of C-band satellite from 5.925 to 6.425 GHz as an uplink band. [ABSTRACT FROM AUTHOR]

The investigation of two half circular patch (HCP) antenna with defected ground structure to operate dual bands is presented in this study for wireless communications. The crescent slots etched on the HCPs are proposed to operate the dual bands of below −10 dB reflection coefficient, with the impedance bandwidth of the first band being 740 MHz (3.01–3.75 GHz) and of the second band being 7120 MHz (6.74–13.86 GHz). The proposed HCP antenna was resonates of 3.36 and 12.17 GHz with −33.9 and −35.47 dB reflection coefficients. This antenna produces a maximum gain of 5.46 and 6.61 dB for these resonating frequencies, respectively. The simulation and measured radiation pattern results are also presented for proposed HCP antenna and it operates for wireless communications and internet of things applications. [ABSTRACT FROM AUTHOR]

This article introduces a wideband monopole antenna with improved peak gain and axial ratio bandwidth that may be applied to various wireless systems and ITU satellite communication systems. The antenna operates in the frequency range of 6 GHz to 8 GHz. The low profile proposed antenna is sufficiently compact (0.8λ0 × λ0, where λ0 be the free space wavelength at fr of 6 GHz) and printed on inexpensive FR4-epoxy substrate (εr = 4.4 and, tanδ = 0.02) that is 1.6 mm thick. The top layer is incorporated with the microstrip feed line and tilted L-shaped strip. On the other side, the bottom layer has also a tilted inverted L-shaped strip. In order to achieve better performance from the proposed antenna, a reflector has been embedded. Peak gain of 8 dBi at 6.2 GHz, 3.4 GHz (5.6 GHz–more than 9 GHz) impedance bandwidth (IBW) and 810 MHz (6.59–7.4 GHz) 3-dB Axial Ratio Bandwidth (ARBW) have been achieved. The proposed antenna has been fabricated and measured. The measured data justifies the simulation. [ABSTRACT FROM AUTHOR]

In this work, a novel triband antenna is developed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX), and Bluetooth application. The proposed antenna is printed on a low-cost FR-4 substrate and has an overall size of 25 mm × 40 mm × 1.6 mm. Coplanar waveguide (CPW) line with characteristic impedance of 50 Ω is used as feed for the designed antenna. A prototype of this antenna is fabricated and tested to validate the simulation results. The measured result shows that the antenna has the triple-band response with frequency bands that correspond to S11<−10 dB 2.36 − 3.17, 3.8 − 4.35, and 5.69 − 6.02 GHz. The measured gains of the antenna at resonant frequencies of 2.61, 4.115 and 5.85 GHz are 0.756, 0.925 and 1.589 dBi, respectively. Maximum decrement in measured gain is only 0.671 dB which is attributed to losses from connectors and cables. A novel approach, based on a combination of a cap-shaped ground plane and gap coupling technique in the form of an interdigital capacitor (IDC), is used to achieve the characteristic of triple frequency bands. Finally, the utility of the proposed antenna is checked with a four-element MIMO antenna. [ABSTRACT FROM AUTHOR]

In this study, a novel reconfigurable triple-band monopole antenna for LoRa IoT applications is fabricated on an FR-4 substrate. The proposed antenna is designed to function at three distinct LoRa frequency bands: 433 MHz, 868 MHz, and 915 MHz covering the LoRa bands in Europe, America, and Asia. The antenna is reconfigurable by using a PIN diode switching mechanism, which allows for the selection of the desired operating frequency band based on the state of the diodes. The antenna is designed using CST MWS® software 2019 and optimized for maximum gain, good radiation pattern and efficiency. The antenna with a total dimension of 80 mm × 50 mm × 0.6 mm (0.12 λ 0 × 0.07 λ 0 × 0.001 λ 0 at 433 MHz) has a gain of 2 dBi, 1.9 dBi, and 1.9 dBi at 433 MHz, 868 MHz, and 915 MHz, respectively, with an omnidirectional H-plane radiation pattern and a radiation efficiency above 90% across the three frequency bands. The fabrication and measurement of the antenna have been carried out, and the results of simulation and measurements are compared. The agreement among the simulation and measurement results confirms the design's accuracy and the antenna's suitability for LoRa IoT applications, particularly in providing a compact, flexible, and energy efficient communication solution for different LoRa frequency bands. [ABSTRACT FROM AUTHOR]

With the continuous development of the IoT, compact wireless communication modules have become indispensable components, and their antennas are gradually being developed from external devices into onboard integrated devices. The serpentine antenna, a variant of the monopole antenna known for its small size and easy integration, is often applied to engineering practices. However, its performance has always been closely affected by the size of the surrounding grounding plane. By conducting a characteristic mode analysis (CMA), this study explored the variation patterns in the ground plane size and the resonant frequency. Based on the simulation results, it was clear that when the ground plane size is less than a quarter of the working wavelength, the ground plane will have a significant effect on the antenna's resonant frequency. Thus, this study further analyzed a serpentine antenna with a grounding branch, and through analysis of the basic law of the influence of grounding structure on the antenna's performance, we found that by adjusting the branch length, the matching performance of the antenna can be effectively improved. Furthermore, by changing the size of the ground plate, the antenna's resonant frequency can be adjusted. Such a conclusion will hopefully provide a reference for future designs of integrated antennas in engineering applications. [ABSTRACT FROM AUTHOR]

Equations that describe elastic wave propagation in a fracturing solid are obtained. It is shown that a solution to an equation for the velocity potential of longitudinal waves of acoustic emission can be represented as the superposition of the fields of an ensemble of radiating cavities known as monopoles. The monopole ensemble parameters are selected so as the structural characteristics of a medium with cavities barely differ from those of a solid. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach to monitoring the healing process of bone fractures using a compact textile monopole antenna integrated into a wearable device. A planar wearable textile ultra-wideband monopole (TUM) antenna is proposed as a sensing element. The antenna is fabricated on the jeans fabric with a thickness of 1 mm, an overall size of $18\times19$ mm2, and operates in an ultra-wideband frequency range (3.22-10.9 GHz). The human arm tibia model is developed in a full-wave simulator in order to estimate the radiation exposure caused by the antenna at near and far field distances. At both field distances, the average specific absorption rate (SAR) values of the model are below the FCC limit. The proposed antenna is experimentally tested on a donor bovine tibia. The proposed system utilizes Unsupervised machine learning (ML) techniques to analyze the received signals from the antenna and provide real-time feedback on the progression of bone fracture healing. The compact and flexible nature of the textile antenna allows for comfortable and unobtrusive wear, making it suitable for long-term monitoring. The integration of Unsupervised ML techniques enables automated analysis of the received signals, eliminating the need for manual interpretation. This work aims to improve the monitoring and assessment of bone fracture healing, leading to more effective treatment strategies and faster recovery times. The experimental results and comparison study with previous literature show that the proposed TUM antenna has several advantages and is suitable for diagnosing bone fractures.

This paper introduces a compact antenna with bandwidth reconfigurable and flexible characteristics for cognitive radio applications. The antenna consists of a monopole as a primary radiator and is excited by a coplanar waveguide to have a single-layer design. To adjust the operating bandwidth (BW) by fixing the lower frequency and varying the upper one, an additional stub is connected to the feeding line. This stub causes a disturbance in the current distribution, which significantly degrades the matching performance. By controlling its length, the rejected band can be changed and thus, the upper frequency is varied. To validate the proposed approach, two stubs are used, and they are connected to the feeding line through two PIN diodes. By switching the ON/OFF state of the diodes, three different states with different operating BW are attained. The fractional BWs for these states are 18.9, 33.2, and 64.3% respectively. Besides, it is also worth noting that the antenna achieves good performance when bent over a curved surface.

A compact asymmetric coplanar strip (ACS)-fed monopole antenna is presented, which operates within the Bluetooth and UWB frequency bands with the capability to simultaneously reject the lower WLAN interfering band. The antenna consists of an inverted right triangle patch monopole loaded by open-ended L-shaped slits not only to produce the additional 2.4 GHz passband to the UWB design but also to achieve stopband characteristics around 5.2 GHz. The conceptual equivalent circuit model as well as characteristic mode analyses are carried out in the design evolution process. The proposed antenna has an overall size of only 20 mm $\times10$ mm, having the smallest area among the so far developed designs, which can be easily integrated within any wireless gadgets. A prototype is fabricated and measured to validate the design, demonstrating the predicted behavior fairly achieved by full-wave analysis. The antenna −10 dB operating bandwidth ranges from 2.38 to 2.42 GHz and from 3.35 to 11 GHz while rejecting from 4.69 to 5.2 GHz. Unlike the unwanted stopband, where the radiation characteristics are adequately deteriorated, the proposed antenna fairly provides stable omni-directional radiation patterns in the ${H}$ -plane, and has an average efficiency (gain) of 87.3% (2.6 dBi) in the desired passband. As far as the antenna transient behavior is concerned, an adequate measured (simulated) system fidelity factor of 0.7 (0.68) is achieved for the transmission of impulse-type UWB signals in the face-to-face configuration.